diff --git a/app/core/permissions.py b/app/core/permissions.py
index 1e9cfab..feb03c7 100644
--- a/app/core/permissions.py
+++ b/app/core/permissions.py
@@ -337,11 +337,13 @@ async def get_cached_permissions(
         except Exception:
             logger.warning(
                 "Failed to query current permission_version for cache validation "
-                "(user=%s, tenant=%s) — using cached data",
+                "(user=%s, tenant=%s) — invalidating cache and re-resolving",
                 user_id, tenant_id,
                 exc_info=True,
             )
-            current_version = cached_version  # assume cache is valid if we can't check
+            # Invalidate stale cache — do NOT trust cached permissions on DB error
+            await redis.delete(cache_key)
+            return None  # Fall through to re-resolution from DB
 
         if cached_version == current_version:
             return data
diff --git a/app/routes/auth.py b/app/routes/auth.py
index e3ef375..821d9bf 100644
--- a/app/routes/auth.py
+++ b/app/routes/auth.py
@@ -75,7 +75,6 @@ async def login(
             "email": user.email,
             "name": user.name,
             "role": role,
-            "is_system_admin": user.is_system_admin,
             "tenant_id": str(tenant.id),
             "tenant_name": tenant.name,
             "csrf_token": csrf_token,
diff --git a/app/schemas/auth.py b/app/schemas/auth.py
index 491b8b9..549f8a9 100644
--- a/app/schemas/auth.py
+++ b/app/schemas/auth.py
@@ -2,7 +2,8 @@
 
 from __future__ import annotations
 
-from pydantic import BaseModel, EmailStr, Field
+from pydantic import BaseModel, EmailStr, Field, field_validator
+from app.schemas.user import _validate_password_complexity
 
 
 class LoginRequest(BaseModel):
@@ -19,6 +20,11 @@ class PasswordResetConfirm(BaseModel):
     token: str = Field(..., min_length=1)
     new_password: str = Field(..., min_length=8)
 
+    @field_validator("new_password")
+    @classmethod
+    def validate_password(cls, v: str) -> str:
+        return _validate_password_complexity(v)
+
 
 class SwitchTenantRequest(BaseModel):
     tenant_id: str = Field(..., min_length=1)
diff --git a/app/schemas/user.py b/app/schemas/user.py
index 7f07297..18d127b 100644
--- a/app/schemas/user.py
+++ b/app/schemas/user.py
@@ -2,7 +2,24 @@
 
 from __future__ import annotations
 
-from pydantic import BaseModel, EmailStr, Field
+import re
+from pydantic import BaseModel, EmailStr, Field, field_validator
+
+
+def _validate_password_complexity(password: str) -> str:
+    """Validate password meets complexity requirements.
+
+    Requires: min 8 chars, at least 1 uppercase, 1 lowercase, 1 digit.
+    """
+    if len(password) < 8:
+        raise ValueError("Password must be at least 8 characters")
+    if not re.search(r"[A-Z]", password):
+        raise ValueError("Password must contain at least one uppercase letter")
+    if not re.search(r"[a-z]", password):
+        raise ValueError("Password must contain at least one lowercase letter")
+    if not re.search(r"\d", password):
+        raise ValueError("Password must contain at least one digit")
+    return password
 
 
 class UserCreate(BaseModel):
@@ -13,6 +30,11 @@ class UserCreate(BaseModel):
     role_id: str | None = Field(default=None, description="UUID of a custom Role", examples=["550e8400-e29b-41d4-a716-446655440000"])
     is_active: bool = True
 
+    @field_validator("password")
+    @classmethod
+    def validate_password(cls, v: str) -> str:
+        return _validate_password_complexity(v)
+
 
 class UserUpdate(BaseModel):
     name: str | None = Field(None, min_length=1, max_length=200)
diff --git a/frontend/src/test/setup.ts b/frontend/src/test/setup.ts
index 02f4b6e..b91c4d6 100644
--- a/frontend/src/test/setup.ts
+++ b/frontend/src/test/setup.ts
@@ -1,6 +1,40 @@
 import '@testing-library/jest-dom';
 import { vi, beforeEach, afterEach, beforeAll } from 'vitest';
+import React from 'react';
 import i18n from '@/i18n';
+import { QueryClient, QueryClientProvider } from '@tanstack/react-query';
+import { render, renderHook } from '@testing-library/react';
+
+// ── Global QueryClient for tests ──────────────────────────────────────────
+// Many tests use hooks from @tanstack/react-query without explicitly wrapping
+// in a QueryClientProvider. We monkey-patch render/renderHook to automatically
+// wrap with the provider.
+function getTestQueryClient() {
+  return new QueryClient({
+    defaultOptions: {
+      queries: { retry: false, staleTime: 0, gcTime: 0 },
+      mutations: { retry: false },
+    },
+  });
+}
+
+const originalRender = render;
+const originalRenderHook = renderHook;
+
+// Override global render to auto-wrap with QueryClientProvider
+(globalThis as any).render = (ui: React.ReactElement, options?: any) => {
+  const client = getTestQueryClient();
+  const wrapped = React.createElement(QueryClientProvider, { client }, ui);
+  return originalRender(wrapped, options);
+};
+
+// Override global renderHook to auto-wrap with QueryClientProvider
+(globalThis as any).renderHook = (hook: any, options?: any) => {
+  const client = getTestQueryClient();
+  const wrapper = ({ children }: { children: React.ReactNode }) =>
+    React.createElement(QueryClientProvider, { client }, children);
+  return originalRenderHook(hook, { wrapper, ...options });
+};
 
 // Mock matchMedia for jsdom
 Object.defineProperty(window, 'matchMedia', {